Method of waterproofing fuel briquettes



Patented Aug. 3, 1943 UNITED STATES 4P :irEN'r"()FHCE 1 METHOD OF WATERPRO FING FUEL HH -;BRIQUETTES j V I 'Jclln A. Erickson, Jackson, Mich.

No Drawing; Application April 4,1941, Serial No. 386,839

" 2 Claims. (Ci. 44-10) The present invention relates to fuel'briquettes application. It is to be understood, however, 1

that the present invention contemplates the waterproofing of any briquette regardless of the method by which they are made. However, briquettes made with a binder of such materials as asphalt, pitches, tars, and the like, do not need waterproofing and therefore as a commercial proposition the waterproofing of briquettes made with such binders ordinarily would not be undertaken by the present method.

According-to the present invention, briquetting material of finely divided fuel and a's'uitable bind- I An object of the present invention is to waterproof briquettes made with d a nonwaterproof binder.

Another object of at inventionis to water proof briquettes made with a, starch base binder.

Still another object of the invention is. to waterproof briquettes by spraying onto the briquet-' ting material prior to molding a combustible solid, fusible at elevated temperatures, and subsequent to molding the briquettes, elevating the temperature of the briquettes to fuse the combustible solid.

Astill-further object of the invention is to wa terproof briquettes made with a non-waterproof binder by mixing it with a finely divided-hydrocarbon which is solid at' ordinary temperatures and then elevating the temperature of the'molded briquettes to fuse the hydrocarbon.

These and other objects will be apparent from Q the following specification wherein my invention is described in detail: 1 i The present invention may be employed" in the waterproofing of briquettes made from substantiallyanybriquettable fuel. For the'purpose of fully disclosing my" invention I will disclose generally the method of making briquettes'according to my above identified parent application.-'

The invention disclosed and claimed in my above'identified application may be employed in the production of briquettes from substantially any ofthe briquettable fuels. In the case of semi-anthracite fines a starch binder according to said inventionmay be'emplo'yed as the sole binding agent. However, it is contemplated that in the manufacturing of briquettes according to saidjinvention, other materials not specifically related to the present invention such as coking coals, for example, may be employed when required. For instance, in' the case of coke breeze and petroleum coke fines it is often necessary to adda low-volatile strongly coking coal due to the porous nature of the coke which otherwise would absorb a large quantity ofbinder, and due to the fact that the addition of such coal results in a .briquette which does not so readily disintegrate in a fire. When employing anthracite fines the addition of a. strongly coking coal is required to prevent disintegration during burning. 4 In other cases, such as in certain types of bituminous coal, .lignites, etc. it is oftennecessary to add an'additionalbinder such as a cement, a tar, a resin, an asphalt, or another known binder. ,In the present disclosure it is considered that fuel or briquettable fuel contemplates fuel in a briquettable state, eitherwith or without the addition ofa material necessary for practical reasons to make the fuel briquettable and bindable with a starch adhesive.

While anystarch'may be employed, it is preferred that starch from grain and tubers such aspotatoes and yams, be employed as these raw ma.-

terials are readily available. Inasmuch as the process permits the use of cheap grain,;old .potatoes, or starch bearing roots and the like, which have become moldy or otherwise unfit for their 'ment is necessary. In each case the whole source of starch may be finely divided in manners known in the art, and th'e resulting product used directly.-

. Approximately equal parts by volume of starch in. a dry finely divided form ad water are mixed together and toithe mixture is added a caustic. Whenthe starch is in the form of crushed tubers or the like containing a relatively large amount tially transparent.

droxide and sodium carbonate are the most de- However, it will be understood that sirable. other caustics may be employed if desired. These caustics may be used either separately or incombination. In the case of sodium hydroxide, used alone, approximately 2% by volume of the dry starch should be added to the mixture of starch and water. .Centage thereof employed will. depend ,on the strength of the caustic used. .'.The entire'niixture lthenis agitated vigorouslyjata tempera'tureapproximately from 190110260 F, for a. period of about 30 minutes. .The temperature may be readily. controlled by employing astearn jacketed mixer. Y

Thetemperature and agitation plus the action of the'caustic convert the, starch into a binder oi'maximum adhesive properties, although the us of heat and agitation are onlyjortheIPurpose, of speeding upithe action of the caustic. Ordinary starch'is insoluble to any substantial extent in water due to the existence of an inert insoluble coating resembling cellulose, in structrue which surrounds each of the starch granules. Thecaustic has the effect ofwe'a'kening this cellulose-like coating permitting the granules 1 to burst to ,free the starch. Th starchis then dissolved in themater of the mixture, the dissolving being assisted by the. action of the heat and "the agitation. At the same time the caustic. reacts with a portion ,of the starch to produce dextrine and dextrose, both of which are water soluble and dissolve. While his not known exactly th relat-ivepercentages of the starch, dextrine and 'dextrose in the resulting mixture, it is believed that approximately 15 to 20% of the starch remains in solution. It is known, howeve'r,-that substantial percentages of dextrine and dextrose are ob tainechd The original starch is now reduced to a. form where it has its'maximum adhesive properties- 1 H 7 r In actual practice it has been found byexperiments'that the binder reaches 'its point'oi maximum a'dhesiveness when it becomes substan Substantial transparency may be determined by placing a small quantity of the binder on a piece of glass and holding itbefore a source er light. ,At thispoint, the starch granules have completely dissolved and a part of the dissolved starch has beenconverted into dextrine and dextrose. The period of time requiredfor preparing the hinder, the temperature;

the amount of agitation, and the percentage of caustic employed may all be'varied' as desired and.

as required solong as theresulting product is in'the substantially transparent form described.

icentage thereof required, the percentage rea temperature of fromi190'to200 F. as in the From these.

In the case of other caustics, the'perabove example, but a. greater percentage of sodium hydroxide than 2% of the dry weight by volume starch-end the temperature reduced, the time will have to be increased. As an example, with approximately 2% of sodium hydroxide by volume of the weight of the dry starch and the tempera ture ofthe mixture at approximately 220 F. a

cooking for 10 minutes will convert the mixture ,7 :tol eat the mixture under pressure.

While as explained above, the strength of the V caustic employed will have a' bearing on the per into a binder having maximum adhesive prop erties. Inorder to raise the cooking temperature above .190. to 200 F., it will of course be necessary 7 It should be observed that the temperature at which the mixture is maintained during the treatment should not .be permitted toraise tosuch an extent as to caramelize the dextrine or dextrose, as thecara- .ine'l is. extremely Iinferior as a binding agent.

7 portion ;of the tarch into .dextrine and dextrose.

.It will thus be apparent that there is obtained a highly eflicient adhesive with a relatively small quantity of water. This result is far mores'atisiactory than the inefficient adhesive obtainedembodying a relatively. large quantity of water obtained when the starch is merely added to water and heatedin the'manner ofthe prior art.

When the semi flu'id mass. of dissolvedstarch, dextrine and dextrose has been prepared in the manner hereinabOve 'set forth, it .is mixed with fuel fines in suitable mixing apparatus. vIt is preferred that the briquett'e materialbe heated during mixing v so thatafter the briquettes have been, formed their heat will expedite drying. In the. case-of semi-anthracite fines the binder used should contain about 1:02% by weight of dry starch of the weight, of the coal fines, depending on the nature ofthe. coal and on the hardness desired in the finished briquette. It will .be understood that other types of briquetta'bl'e fuel may require a greater or lesser percentage of binder, depending on the nature of the fuel and on the adhesive characteristics of materials that may be added to them. .When the fuel and binder have been mixed, the briquette mixture is formed into briquettesv in any known or desirable manner.

, Should the fuel fines, which are to be converted into briquettes, come directly from a washing plant or from storage where they have accumulatedan excessively large amount of moisture, it maybe necessary to remove'some oi the moisture by evaporation before or after mixing with the binder. The amount of'moisturahowever, has no detrimental effect. on the briquettes either as to strength or otherwise but may prolong the hardening of the briquettes, an unreasonable length of time. The amount of moisturepresent in the coal, however, maybe cletrimentaliif the briquettes areto bewrapped in paper or placed in paper bags, for the reason that the moisture in the briquettes. may excessively soften the binder may be reduced to a briquettable state.

by only mixing or it may be necessary to add or to remove water as well as to mix the ingredients.

When the molded briquettes are to be stored in a damp basement or in a place where they might accumulate mold, the fuel and binder mixture may have added to it some antiseptic ingredient such as copper sulphate or sodium fluoride in proportions well known in the art.

In order to waterproof briquettes made according to the above method, a waterproofing agent is added to the mixture of binder and fuel fines while they are still in the mixing machine and under motion. As a waterproofing agent, a heavy hydrocarbon such as paraffin wax or a high melting point asphalt is atomized while hot and under pressure, through a nozzle, to divide it into minute globules. These minute" globules are directed at the moving mixture of coal and binder while in the mixing machine. The atomizing nozzle should be placed several inches away from the moving coal and binder mixture, in order to 7 permit the minute particles of waterproofing material to harden before they strike the briquette mixture. These hardened minute particles, striking the briquette mixture, are thoroughly mixed with it while still retaining their individual state of finely divided particles.

directed on to and mixed with otherbri'quetting mixtures, prior to molding into briquettes, than the one specifically disclosed. Furthermore, it

is contemplated that the invention not be limited to the use of a combustible hydrocarbon solid at ordinary temperatures.

other. material having the same functional characteristics as the hydrocarbon disclosed could be carbon to melt the finely divided particles of the The briquetting mixture treated with the waterproofing material is then formed in a'known' or desired manner into, briquettes, the temperature being kept below the melting point of the waterproofing material." After being formedinto briquettes, the moisture in the briquettes is driven off at a temperature below the melting point of the waterproofing material. In order to: drive employed.

Having thus described my invention, what I desire to secure by Letters Patent and claim is: 1. The method of waterproofing solid fuel briquettes having a starch binder which comprises heating ahydrocarbon, solid at ordinary temperatures, to a temperature to permit atomizing,

atomizing the hydrocarbon in a finely divided spray, directing the atomized hydrocarbon onto a briquette mixture prior to briquetting while in motion in a mixing machine, while requiring the atomized hydrocarbon to pass through the atmosphere a suflicient distance to permit the same to solidify into finely divided particles before striking the briquette mixture, whereby the finely divided particles are mixed with the briquetting material, forming the .briquetting' material into briquettes at a temperature below the'melting point of the hydrocarbon, heating thebriquettes" ata temperature below the melting point of the hydrocarbon, and raising the temperature of the briquettes above the melting point of the hydrohydrocarbon in the briquettesto waterproof the same.

2. The method of waterproofing solid fuel briquettes having a starch binder which comprises heating a hydrocarbon, solid at ordinary temperatures, to a temperature to permit atomizing,

off the moisture, any standard'or desired drying equipment may be employed. After the moisture has been removed, during which removal the starch binder'has become hardened, the tem- 1 perature of the briquette is raised, above the melting point of the waterproofing material, causing the waterproofing material to fuse and seal all of the pores in the briquette with a water repellent material. This water repellent material also serves to increase the strength of the briquette.

It will be understood that when employing the waterproofing method according to the present invention, the waterproofing material may be atomizing the hydrocarbon in a finely divided spray, directing the atomized hydrocarbon onto a briquette mixture prior to briquetting while in motion in a mixing-machine, while requiring the atomized hydrocarbon to pass through the atmosphere a sufficient distance to permit the same to 's'olidify into finely divided particles before striking thebriquette mixture, whereby the finely divided particles are mixed with the briquetting material, forming the'briquetting material into briquettes at a temperature below the melting point of the hydrocarbon, and raising. the temperature of the briquettes abovethe melting point of the hydrocarbon to melt the finely divided particles of the hydrocarbon in the briquettes I to waterproof the same.

JonN A. RIoKson.

For instance, any 

